clock.c

RTOS系统

/* $Id: //depot/software/SDK/Triscend/a7hal/src/clock.c#23 $ */
/*
 **********************************************************
 *  clock.c
 *  Copyright(C) 2001-2003 Triscend Corporation. All Rights Reserved.
 *  This file is licensed under the terms of Triscend SDK License Agreement. 
 **********************************************************
 */
#include "hal_conf.h"
#if A7HAL_USE_CLOCK
/**
 * \file
 * Contains functions to get/set the CPU clock speed.
 * The functions within this file are only accessible if A7HAL_USE_CLOCK
 * is #defined as YES in hal_conf.h
 */

/** \defgroup clock Clock Driver
 * @{
 */

#include "triscend_a7.h"
#include "clock.h"

#ifdef __KERNEL__
#include <linux/autoconf.h>

#ifndef CONFIG_OSC_FREQ
  #define CONFIG_OSC_FREQ	25000000
#endif

#endif

static unsigned long a7hal_ring_freq = A7HAL_RING_FREQ;
#ifdef __KERNEL__
static unsigned long a7hal_xclk_freq = CONFIG_OSC_FREQ;
#else
static unsigned long a7hal_xclk_freq = A7HAL_XCLK_FREQ;
#endif
static unsigned long a7hal_xtal_freq = A7HAL_XTAL_FREQ;

/**
 * \brief Initialize the clock driver.
 *
 * This function is called from the a7hal_driverInit function
 * to initialize the clock driver. It calls a7hal_clock_reset
 * to set the default clock values.
 *
 * \return N/A
 *
 * \see a7hal_clock_reset, a7hal_driverInit
 */
void a7hal_clock_init( void )
{
    a7hal_clock_reset(  );
}

/**
 * \brief Get the clock device base address.
 *
 * \return This function always returns 0.
 *
 * \note The clock driver accesses a number of clock registers,
 * there is no one base address for this device.
 */
unsigned long a7hal_clock_getDeviceAddress( void )
{
    return ( 0 );
}

/**
 * \brief Reset the clock driver.
 *
 * This function sets the the PLL, external clock,
 * and ring oscillator to their default values.
 *
 * \return N/A
 *
 * \note This function will not change the actual
 * clock speed, since this is controlled by hardware,
 * it does not write to any clock registers. This function
 * is for software configuration only.
 */
void a7hal_clock_reset( void )
{
    a7hal_ring_freq = A7HAL_RING_FREQ;
#ifdef __KERNEL__
    a7hal_xclk_freq = CONFIG_OSC_FREQ;
#else
    a7hal_xclk_freq = A7HAL_XCLK_FREQ;
#endif
    a7hal_xtal_freq = A7HAL_XTAL_FREQ;
}

/**
 * \brief Get the CPU clock speed.
 *
 * This function is called to return the CPU clock frequency in Hz.
 * It can be called before or after RAM is initialized, if called
 * before RAM is initialized a non zero value MUST be specified for
 * the 'noRAM' parameter. In this case the clock frequency returned
 * will be based on the values of A7HAL_RING_FREQ, A7HAL_XCLK_FREQ,
 * and A7HAL_XTAL_FREQ defined in clock.h
 *
 * If the 'noRAM' parameter is zero, the clock frequency returned
 * will be based on the values set by a7hal_clock_setPllClock,
 * a7hal_clock_setXClock, and a7hal_clock_setRing.
 *
 * \param noRAM Should be non zero if this function is called before RAM is initialized
 *
 * \return Clock frequency in Hz.
 *
 * \see a7hal_clock_setPllClock, a7hal_clock_setXClock, a7hal_clock_setRing, a7hal_sdram_init
 *
 * \note The a7hal_clock_get... and a7hal_clock_set... function
 * calls use global variables to store the clock values. These
 * global variables will proberly not exist untill after the
 * RAM system has been initialized. For this reason, the 'noRAM'
 * parameter is used to tell this function to use the #defined
 * clock values in clock.h
 */
unsigned long a7hal_clock_getFreq( int noRAM )
{
    unsigned int freq;
    unsigned long local_a7hal_ring_freq;
    unsigned long local_a7hal_xclk_freq;
    unsigned long local_a7hal_xtal_freq;
#if defined(A7VE) || defined(A7VC) || defined(A7VT) || defined(A7VL)
    unsigned long feedbackDivider;
    unsigned long outputDivider;
    unsigned long referenceDivider;
#else
    unsigned int scale;
#endif

    /* If this function is called before the SDRAM
     * is initialized, we can not use any global vars
     * so we use the hard coded values for the clocks
     * defined in clock.h
     */
    if ( noRAM )
    {
        local_a7hal_ring_freq = A7HAL_RING_FREQ;
#ifdef __KERNEL__
        local_a7hal_xclk_freq = CONFIG_OSC_FREQ;
#else
        local_a7hal_xclk_freq = A7HAL_XCLK_FREQ;
#endif
        local_a7hal_xtal_freq = A7HAL_XTAL_FREQ;
    }
    else
    {
        local_a7hal_ring_freq = a7hal_ring_freq;
        local_a7hal_xclk_freq = a7hal_xclk_freq;
        local_a7hal_xtal_freq = a7hal_xtal_freq;
    }

    freq = local_a7hal_ring_freq;

    /*
     * if (clock is not ring)
     *   if (clock is xtal/PLL) calculate freq from PLL settings.
     *   else clock is ext.osc. and user MUST define clock freq.
     *   else clock is ring and approximate freq = 20,000,000.
     */
    if ( GET_BIT( SYS_CLOCK_CONTROL_REG, CLK_SEL_BIT ) )
    {
        if ( GET_BIT( SYS_CLOCK_CONTROL_REG, PLL_SEL_BIT ) )
        {
#if defined(A7VE) || defined(A7VC) || defined(A7VT) || defined(A7VL)
            feedbackDivider = GET_FIELD( SYS_PLL_CONTROL_REG,
                                         PLL_CLKF_FIELD, NBITS_PLL_CLKF ) + 1;

            outputDivider = GET_FIELD( SYS_PLL_CONTROL_REG,
                                       PLL_CLKOD_FIELD, NBITS_PLL_CLKOD ) + 1;

            referenceDivider = GET_FIELD( SYS_PLL_CONTROL_REG,
                                          PLL_CLKR_FIELD,
                                          NBITS_PLL_CLKR ) + 1;

            /*
             * Is the input to the PLL the 32KHz xtal or the external osc.
             */
            if ( GET_BIT( SYS_PLL_CONTROL_REG, PLL_REFSEL_BIT ) )
            {
                freq = ( local_a7hal_xclk_freq /
                                ( referenceDivider * outputDivider )) * feedbackDivider;
            }
            else
            {
                freq = ( local_a7hal_xtal_freq * feedbackDivider ) /
                    ( referenceDivider * outputDivider );
            }

#else
            freq =
                local_a7hal_xtal_freq * GET_FIELD( SYS_CLOCK_CONTROL_REG,
                                                   PLL_DIV_FIELD,
                                                   NBITS_PLL_DIV );
            scale =
                GET_FIELD( SYS_CLOCK_CONTROL_REG, PLL_SCALE_FIELD,
                           NBITS_PLL_SCALE );
            while ( scale )
            {
                freq >>= 1;
                scale >>= 1;
            }
#endif
        }
        else
        {
            freq = local_a7hal_xclk_freq;
        }
    }

    return freq;
}

/**
 * \brief Set the frequency of the clock that drives the PLL.
 *
 * \param freq Frequency in Hertz of the PLL driver clock
 *
 * \return N/A
 *
 * \see a7hal_clock_getPllClock, a7hal_clock_getFreq
 *
 * \note This function will not change the actual
 * clock speed, since this is controlled by hardware,
 * it does not write to any clock registers. This function
 * is for software configuration only.
 */
void a7hal_clock_setPllClock( unsigned long freq )
{
    a7hal_xtal_freq = freq;
}

/**
 * \brief Get the frequency of the clock that drives the PLL.
 *
 * \return The frequency in Hz of the clock that drives the PLL.
 *
 * \see a7hal_clock_getPllClock, a7hal_clock_getFreq
 *
 * \note The default value for clock that drives the PLL is A7HAL_XTAL_FREQ,
 * defined in clock.h
 */
unsigned long a7hal_clock_getPllClock( void )
{
    return ( a7hal_xtal_freq );
}

/**
 * \brief Set the frequency of the external clock.
 *
 * \param freq Frequency in Hertz of the external clock
 *
 * \return N/A
 *
 * \see a7hal_clock_getXClock, a7hal_clock_getFreq
 *
 * \note This function will not change the actual
 * clock speed, since this is controlled by hardware,
 * it does not write to any clock registers. This function
 * is for software configuration only.
 */
void a7hal_clock_setXClock( unsigned long freq )
{
    a7hal_xclk_freq = freq;
}

/**
 * \brief Get the frequency of the external clock.
 *
 * \return The frequency in Hz of the external clock.
 *
 * \see a7hal_clock_setXClock, a7hal_clock_getFreq
 *
 * \note The default value for the external clock is A7HAL_XCLK_FREQ,
 * defined in clock.h
 */
unsigned long a7hal_clock_getXClock( void )
{
    return ( a7hal_xclk_freq );
}

/**
 * \brief Set the frequency of the ring oscillator.
 *
 * \param freq Frequency in Hertz ring oscillator
 *
 * \return N/A
 *
 * \see a7hal_clock_getRing, a7hal_clock_getFreq
 *
 * \note This function will not change the actual
 * clock speed, since this is controlled by hardware,
 * it does not write to any clock registers. This function
 * is for software configuration only.
 */
void a7hal_clock_setRing( unsigned long freq )
{
    a7hal_ring_freq = freq;
}

/**
 * \brief Get the frequency of the ring oscillator.
 *
 * \return The frequency in Hz of the ring oscillator.
 *
 * \see a7hal_clock_setRing, a7hal_clock_getFreq
 *
 * \note The default value for the ring oscillator is A7HAL_RING_FREQ,
 * defined in clock.h
 */
unsigned long a7hal_clock_getRing( void )
{
    return ( a7hal_ring_freq );
}

/** @} */

#endif